000
AXPZ20 KNHC 262311 CCA
TWDEP 

TROPICAL WEATHER DISCUSSION...CORRECTED
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT DEC 26 2009

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 5N78W TO 5N92W 4N105W 8N117W 5N140W.
SCATTERED MODERATE CONVECTION IS WITHIN 180 NM S OF THE AXIS 
E OF 80W AND BETWEEN 82W AND 86W.

...DISCUSSION...

AN UPPER LEVEL TROUGH EXTENDS NE TO SW FROM SW TEXAS AND NORTHERN
MEXICO SW TO 19N112W TO 12N119W WHERE IT BECOMES ILL-DEFINED. TO 
THE OF THE TROUGH THE UPPER LEVEL FLOW IS ZONAL N OF 19N AND VERY
MOIST CONSISTING OF BROKEN HIGH CLOUDS STREAMING EASTWARD MAINLY 
TO THE N OF 24N. A STRONG JET STREAM EXTENDS INTO THE AREA 
THROUGH 25N140W TO 28N127W AND TO ACROSS CENTRAL BAJA 
CALIFORNIA. MAXIMUM JET CORE WIND SPEEDS AS NOTED BY SATELLITE 
DERIVED WIND DATA ARE IN THE RANGE OF 70-120 KT IN THE JET 
STREAM CORE FROM 25N TO 29N BETWEEN 122W AND 131W...AND ALSO 
WITHIN THE REAR ENTRANCE REGION N OF 23N W OF 136W.

THE SOUTHERN EXTENSION OF A NARROW UPPER TROUGH THAT EXTENDS 
FROM THE CENTRAL ATLANTIC SW TO THROUGH THE EASTERN CARIBBEAN 
SEA AND SW TO ACROSS PANAMA TO NEAR 5N80W. THE COMBINATION OF 
LOW LEVEL CONVERGENCE AND UPPER DIFFLUENCE E OF THE UPPER TROUGH 
CONTINUES TO SUPPORT THE CONVECTION ALONG AND NEAR THE ITCZ E OF 
E OF 80W. ELSEWHERE ACROSS THE SE PORTION OF THE AREA...THE 
ATMOSPHERIC ENVIRONMENT REMAINS UNDER MODERATE SUBSIDENCE AS 
NOTED ON SATELLITE WATER VAPOR IMAGERY ALLOWING FOR MOSTLY 
STABLE CONDITIONS TO PREVAIL THERE OUTSIDE THE ITCZ CONVECTION 
MENTIONED ABOVE. MODERATE SUBSIDENCE AND ASSOCIATED STABLE 
ATMOSPHERIC CONDITIONS ARE ALSO EVIDENT W OF THE UPPER TROUGH S 
OF 24N. ONLY SCATTERED TO OCCASIONALLY BROKEN LOW CLOUDS MOVING 
W TO SW WITH POSSIBLE ISOLATED SHOWERS ARE NOTED FROM 10N TO 24N 
W OF 119W. THE UPPER FLOW PATTERN BETWEEN THE TROUGH AND THE 
WESTERN EXTENSION OF MID/UPPER LEVEL RIDGING THAT EXTENDS OVER S 
AMERICA ALONG 5N IS ADVECTING UPPER LEVEL MOISTURE ALONG THE 
COAST OF COLOMBIA NE ACROSS SRN PANAMA...BEFORE IT QUICKLY 
EVAPORATES IN THE DRY AIR UNDER THE MODERATE SUBSIDENCE.

AN UPPER ANTICYCLONE IS CENTERED OVER EASTERN HONDURAS WITH A
RIDGE EXTENDING SW TO A SHARP CREST NEAR 2N111W. A RIDGE ALSO 
EXTENDS NE TO A CREST OVER CENTRAL CUBA. CONVECTION PREVIOUSLY 
MENTIONED IS ENHANCED ALONG THE SOUTHERN PERIPHERY OF THE RIDGE 
NEAR 04N90W...BUT THE DEBRIS MOISTURE REMAINS IN THE SAME AREA. 
DEBRIS MOISTURE FROM FORMER ITCZ CONVECTION IS CONFINED IN A 
TROPICAL PLUME ALONG THE NW PERIPHERY OF THIS UPPER 
RIDGE...ROUGHLY WITHIN 180 NM OF LINE 10N120W TO 20N105W. THE 
MOISTURE FANS OUT OVER THE UPPER LEVELS OF THE GULF OF MEXICO 
AND FLORIDA. OTHERWISE DRY UPPER AIR IS INDICATED OVER THE 
DISCUSSION AREA S OF 18N E OF 105W.
 
AT THE SURFACE...A 1021 MB HIGH PRES IS CENTERED NEAR 26N121W
WITH A RIDGE SE TO 20N107W. IT IS SLOWING DOWN THE EASTWARD
MOTION OF A WEAKENING COLD FRONT THAT EXTENDS FROM 32N127W TO 
25N133W. NE 20 KT ARE OBSERVED WITHIN AN AREA FROM 9N TO 19N W 
OF 128W AND FROM 12N TO 19N BETWEEN 124W AND 128W WITH SEAS OF 
10 TO 15 FT IN NW SWELL. THESE WINDS ARE FOUND OVER THE SOUTHERN 
PERIPHERY OF THE RIDGE. SUBSIDING LARGE NW SWELLS MIGRATING SE
AND S OVER JUST ABOUT THE ENTIRE AREA W OF A LINE FROM 30N117W
TO 13N117W TO 00N120W ARE BEING REINFORCED BY ANOTHER TRAIN OF 
LARGE NW SWELLS IN THE WAKE OF THIS COLD FRONT AND A SECONDARY 
SURGE EXPECTED TO MOVE INTO THE NW PORTION TONIGHT. A WEAK LOW
PRES CENTER OF 1018 MB IS FORECAST TO DROP SE TO NEAR 31N132W
BY SUN AFTERNOON...AND TO NEAR 28N124W AS 1017 MB BY MON 
AFTERNOON WITH FRONT FROM ITS CENTER SW TO NEAR 21N133W. A SWATH 
OF MINIMAL GALE FORCE WINDS MAY BRIEFLY MOVE INTO THE AREA LATE 
SUN NIGHT IN THE W QUADRANT OF THE LOW BETWEEN 150 NM AND 270 
NM...BUT QUICKLY DIMINISH TO 25 KT BY MON MORNING. MODELS HAVE 
WEAKENED WINDS WITH THIS LOW SINCE YESTERDAY...SO THERE IS A 
CHANCE THAT WINDS MAY NOT REACH GALE FORCE. SEAS MAY REACH UP TO 
17 FT IN NW SWELL IN THE AREA OF THESE FORECAST WINDS.

GAP WINDS...
GULF OF TEHUANTEPEC...NORTHERLY WINDS ARE EXPECTED TO INCREASE 
TO 20 TO 25 KT IN THE GULF OF TEHUANTEPEC SUN AFTERNOON...AND 
CONTINUE TO GRADUALLY INCREASE INTO EARLY NEXT WEAK.

FOR ADDITIONAL INFORMATION PLEASE VISIT 
HTTP://WWW.HURRICANES.GOV/MARINE
  
$$
AGUIRRE